The present invention relates to a method and a device for feeding a sheet such as a developer sheet so as to overlap another sheet such as an exposed photosensitive pressure-sensitive sheet with an image recorded thereon for transferring the image from said photosensitive pressure-sensitive sheet to said developer sheet in a developing unit in an image recording apparatus.
U.S. Pat. No. 4,399,209, for example, discloses an imaging system in which a photosensitive pressure-sensitive sheet exposed to light bearing an image and a developer sheet are superposed on each other and pressed together to develop the image on the developer sheet. Some image output apparatus incorporating such an imaging system have already been proposed. Such an image output apparatus generally employs a roll of photosensitive pressure-sensitive sheet and a cut developer sheet. It has been necessary in the image output apparatus to control the timing of starting to feed the developer sheet so that the developer sheet will be brought into exact registry with a desired position on the photosensitive pressure-sensitive sheet. Heretofore, a complex and highly sophisticated control unit has been required to control the timing of starting to feed the developer sheet for registry with the photosensitive pressure-sensitive sheet.
Some conventional sheet feeding devices in image recording apparatus include a pair of gripper rollers which are either spaced by a fixed gap from each other or in contact with each other. The gripper rollers themselves serve as a stopper for temporarily stopping the sheet feeding by the abutment of the leading edge of the sheet thereagainst. For feeding a sheet such as a developer sheet with the gripper rollers, the gripper rollers start rotating to feed the sheet upon elapse of a preset time after a switch positioned in front of the gripper rollers is pushed. If, however, the sheet is not accurately in abutment with the gripper rollers, the sheet will not be fed by the gripper rollers. If the sheet as it engages the gripper rollers is skeWed with respect to the gripper rollers, the sheet will be fed in a slanting manner relative to a sheet path.